Sexual Reproduction in Plants : NCERT / CBSE Notes

Reproduction:
The process of producing young ones that look like the parents is called reproduction.  Plants reproduce either sexually or asexually.  Plants reproduce sexually by the most attractive part, called the flower.
Sexual Reproduction in Plants, CBSE / NCERT Notes, Class 7

  • The stalk of a flower is called the pedicel.
  • All floral parts are arranged on its flattened tip, called the receptacle.
  • The stamens and the pistil are the reproductive parts of a flower.
  • The anther contains pollen sacs that produce pollen grains
  • Pollens are the male reproductive unit of the flower.
  • Pistil is the female reproductive part of the flower.
  • Bisexual flowers contain both – the stamens and the pistil. For example, mustard and rose.
  • Unisexual flowers have either the stamens or the pistil. For example, cucumber, maize and watermelon.

Pollination:

  • The transfer of pollen grains from one flower to another is called pollination. Pollen grains transfer from one flower to another by pollinating agents.
  • The transfer of pollen grains from the anther of one flower, to the stigma of another flower on another plant of the same type, is known as cross-pollination.  
  • The transfer of pollen grains from the anther to the stigma of the same flower or to the stigma of another flower on the same plant, it is termed self-pollination.  

Fertilisation:

The zygote is formed by the fusion of the male and female gametes.  This process is called fertilisation.  After fertilisation, the ovary changes into a fruit. It may be either fleshy or dry. 
Seeds and fruits are dispersed by agents like wind, water, animals and humans.
The pods present in these seeds dry up in the sun. This causes the pod to split with great force, thereby dispersing the seeds away from the parent plant. 
Some seeds are dispersed by a special method called explosion. Examples are mustard, ladies finger, peas, bean, pod and castor.

Must Read : Asexual Reproduction in Plants

Reproduction:
The process by which all living things produce young ones that look like themselves is called reproduction. Plants reproduce either sexually or asexually.
  • Flowers are the most attractive and the reproductive parts of a plant. A flower may have a stalk-like structure, called the pedicel. The sepals, petals, stamens and the pistil are arranged on its flattened tip, called the receptacle.
  • The stamens are the male reproductive parts.
  • The pistil is the female reproductive part.
  • The pistil produces gametes. Gametes are the reproductive cells.
  • The anther is a knob-like structure of the stamen.
  • The filament is the long part of the stamen.
  • The anther contains pollen sacs, which produce pollen grainsPollen grains are yellow powdery particles containing the male gametes or the male reproductive cells.
  • The number of stamens in a flower are three or five, or in multiples of three of five.
  • The ovary contains numerous ovules.
  • Each ovule contains a female gamete or egg cell.
  • The basal swollen part of the pistil is the ovary.
  • The pistil is the centrally located female reproductive part of a flower.
  • The stigma and the style are major parts of the pistil.
  • A flower with a stamen and a pistil is a bisexual flower.
  • A flower that has either a stamen or a pistil is a unisexual flower.
  • Pollen grains from the stamen fall on the stigma for reproduction to take place.
  • The transfer of pollen from the stamen to the stigma is known as pollination.
  • The transfer of pollen from the stamen to the stigma of the same flower is called self-pollination.
  • The transfer of pollen from the stamen of one flower to the stigma of another is called cross-pollination.
  • zygote is formed by the fusion of a male gamete and a female gamete.
  • After fertilisation, the zygote develops into an embryo.
  • The ovule develops into a seed.
  • The seeds of the coconut tree fall into water when they ripen.
  • The pond iris is adapted for seed dispersal through water.
  • Seed dispersal is a method of dispersal of seeds through water, animals, birds, wind or insects.
  • Bursting is also a method to disperse seeds, found in balsam.
  • Xanthium fruits have spines to get attached to the fur of animals or clothes.
  • Drumstick seeds are dispersed by the explosion of fruits.


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